Azeotrope-like compositions of 1,1-dichloro-1-fluoroethane, dichlorotrifluorethane, nitromethane and methanol or ethanol

ABSTRACT

Azeotrope-like compositions comprising 1,1-dichloro-1-fluoroethane, dichlorotrifluoroethane, nitromethane and ethanol or methanol are stable and have utility as degreasing agents and as solvents in a variety of industrial cleaning applications including cold cleaning and defluxing of printed circuit boards.

This application is a continuation of application Ser. No. 345,732 filedMay 1, 1989 now abandoned. Ser. No. 345,732 is a continuation-in-part ofpatent application Ser. No. 297,467 filed Jan. 17, 1989, which is nowU.S. Pat. No. 4,894,176, and is a continuation-in-part application ofpatent application Ser. No. 290,124 filed Dec. 27, 1988 now abandoned.

DESCRIPTION

1. Field of the Invention

This invention relates to azeotrope-like or essentially constant boilingmixtures of 1,1-dichloro-1-fluoroethane, dichlorotrifluoroethane,nitromethane and methanol or ethanol. These mixtures are useful in avariety of vapor degreasing, cold cleaning and solvent cleaningapplications including defluxing.

2. Cross-Reference to Related Applications

Co-pending, commonly assigned application Ser. No. 204,340, filed Jun.9, 1988, now U.S. Pat. No. 4,836,947 discloses azeotrope-like mixturesof 1,1-dichloro-1-fluoroethane and ethanol.

Co-pending, commonly assigned application Ser. No. 330,252, filed Mar.29, 1989, now U.S. Pat. No. 4,863,630 discloses azeotrope-like mixturesof 1,1-dichloro-1-fluorethane, dichlorotrifluoroethane and ethanol.

Co-pending, commonly assigned application Ser. No. 189,932 filed May 3,1988, now U.S. Pat. No. 4,842,764 discloses azeotrope-like mixtures of1,1-dichloro-1-fluorethane and methanol.

Co-pending, commonly assigned application Ser. No. 297,467, filed Jan.17, 1989, now U.S. Pat. No. 4,894,176 which is a continuation-in-part ofapplication Ser. No. 290,124, filed Dec. 27, 1988, now abandoneddiscloses azeotrope-like mixtures of 1,1-dichloro-1-fluorethane,dichlorotrifluoroethane and methanol.

BACKGROUND OF THE INVENTION

Vapor degreasing and solvent cleaning with fluorocarbon based solventshave found widespread use in industry for the degreasing and otherwisecleaning of solid surfaces, especially intricate parts and difficult toremove soils.

In its simplest form, vapor degreasing or solvent cleaning consists ofexposing a room temperature object to be cleaned to the vapors of aboiling solvent. Vapors condensing on the object provide clean distilledsolvent to wash away grease or other contamination. Final evaporation ofsolvent from the object leaves behind no residue as would be the casewhere the object is simply washed in liquid solvent.

For difficult to remove soils where elevated temperature is necessary toimprove the cleaning action of the solvent, or for large volume assemblyline operations where the cleaning of metal parts and assemblies must bedone efficiently and quickly, the conventional operation of a vapordegreaser consists of immersing the part to be cleaned in a sump ofboiling solvent which removes the bulk of the soil, thereafter immersingthe part in a sump containing freshly distilled solvent near roomtemperature, and finally exposing the part to solvent vapors over theboiling sump which condense on the cleaned part. In addition, the partcan also be sprayed with distilled solvent before final rinsing.

Vapor degreasers suitable in the above-described operations are wellknown in the art. For example, Sherliker et al. in U.S. Pat. No.3,085,918 disclose such suitable vapor degreasers comprising a boilingsump, a clean sump, a water separator, and other ancillary equipment.

Cold cleaning is another application where a number of solvents areused. In most cold cleaning applications, the soiled part is eitherimmersed in the fluid or wiped with rags or similar objects soaked insolvents and allowed to air dry.

Fluorocarbon solvents, such as trichlorotrifluoroethane, have attainedwidespread use in recent years as effective, nontoxic, and nonflammableagents useful in degreasing applications and other solvent cleaningapplications. Trichlorotrifluoroethane has been found to havesatisfactory solvent power for greases, oils, waxes and the like. It hastherefore found widespread use for cleaning electric motors,compressors, heavy metal parts, delicate precision metal parts, printedcircuit boards, gyroscopes, guidance systems, aerospace and missilehardware, aluminum parts and the like.

The art has looked towards azeotropic compositions including the desiredfluorocarbon components such as trichlorotrifluoroethane which includecomponents which contribute additionally desired characteristics, suchas polar functionality, increased solvency power, and stabilizers.Azeotropic compositions are desired because they do not fractionate uponboiling. This behavior is desirable because in the previously describedvapor degreasing equipment with which these solvents are employed,redistilled material is generated for final rinse-cleaning. Thus, thevapor degreasing system acts as a still. Unless the solvent compositionexhibits a constant boiling point, i.e., is an azeotrope or isazeotrope-like, fractionation will occur and undesirable solventdistribution may act to upset the cleaning and safety of processing,preferential evaporation of the more volatile components of the solventmixtures, which would be the case if they were not an azeotrope orazeotrope-like, would result in mixtures with changed compositions whichmay have less desirable properties, such as lower solvency towardssoils, less inertness towards metal, plastic or elastomer components,and increased flammability and toxicity.

The art is continually seeking new fluorocarbon based azeotropicmixtures or azeotrope-like mixtures which offer alternatives for new andspecial applications for vapor degreasing and other cleaningapplications. Currently, of particular interest, are such azeotrope-likemixtures which are based on fluorocarbons which are considered to bestratospherically safe substitutes for presently used fully halogenatedchlorofluorocarbons. The latter are suspected of causing environmentalproblems in connection with the earth's protective ozone layer.Mathematical models have substantiated that hydrochlorofluorocarbons,such as 1,1-dichloro-1-fluoroethane (HCFC-141b) anddichlorotrifluoroethane (HCFC-123 or HCFC-123a), will not adverselyaffect atmospheric chemistry, being negligible contributors to ozonedepletion and to green-house global warming in comparison to the fullyhalogenated species.

U.S. Pat. No. 3,936,387 discloses the azeotropic composition of methanolwith 1,2-dichloro-1-fluoroethane (HCFC-141). U.S. Pat. No. 4,035,258discloses the azeotropic composition of ethanol with HCFC-141.

L. Horsley, AZEOTROPIC DATA-III, 70 (1973) discloses azeotropiccompositions of nitromethane and methanol or ethanol.

U.S. Pat. No. 4,816,174 discloses azeotropic compositions of HCFC-141b,methanol and nitromethane.

U.S. Pat. No. 4,816,176 discloses azeotropic compositions of2,2-dichloro-1,1,1-trichloroethane (HCFC-123) or1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a), methanol andnitromethane.

U.S. Pat. No. 4,816,175 discloses azeotropic compositions of HCFC-123 orHCFC-123a, methanol, nitromethane and cyclopentane.

It is an object of this invention to provide novel azeotrope-likecompositions based on HCFC-141b and dichlorotrifluoroethane which areliquid at room temperature and which will not fractionate under theprocess of distillation or evaporation, which are useful as solvents foruse in vapor degreasing and other solvent cleaning applicationsincluding defluxing applications.

Another object of the invention is to provide novel environmentallyacceptable solvents for use in the aforementioned applications.

Other objects and advantages of the invention will become apparent fromthe following description.

DESCRIPTION OF THE INVENTION

In accordance with the invention, novel azeotrope-like compositions havebeen discovered comprising HCFC-141b, dichlorotrifluoroethane,nitromethane and methanol or ethanol. The dichlorotrifluoroethanecomponent can be either of its isomers1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) or1,2-dichloro-1,2,2-trifluoroethane (HCFC-123a), or mixtures thereof. Thepreferred isomer is HCFC-123.

Dichlorotrifluoroethane and HCFC-141b do not form binary azeotropesystems.

In one embodiment, the azeotrope-like compositions of the inventioncomprise from about 62.5 to about 97.9 weight percent of HCFC-141b, fromabout 2.0 to about 35.5 weight percent of dichlorotrifluoroethane, fromabout 0.02 to about 0.3 weight percent of nitromethane and from about0.1 to about 3.0 weight percent ethanol.

In a preferred embodiment of the invention, the azeotrope-likecompositions of the invention comprise from about 72.0 to about 94.7weight percent of HCFC-141b, from about 3.0 to about 26.0 weight percentof dichlorotrifluoroethane, from about 0.05 to about 0.3 weight percentof nitromethane and from about 0.3 to about 2.0 weight percent ethanol.

In a still more preferred embodiment of the invention, theazeotrope-like compositions of the invention comprise from about 75.0 toabout 90.0 weight percent of HCFC-141b, from about 5.0 to about 24.7weight percent of dichlorotrifluoroethane, from about 0.05 to about 0.2weight percent of nitromethane and from about 0.3 to about 1.8 weightpercent ethanol.

In the most preferred embodiment of the invention, the azeotrope-likecompositions of the invention comprise from about 77.2 to about 90.0weight percent of HCFC-141b, from about 5.0 to about 21.7 weight percentof dichlorotrifluoroethane, from about 0.05 to about 0.2 weight percentof nitromethane and from about 0.3 to about 1.5 weight percent ethanolwhich exhibits a boiling point of 33.0° C. at 760 mm Hg.

The term "azeotrope-like" is also used herein for a composition ofHCFC-141b, dichlorotrifluoroethane, nitromethane, and methanol becausethe composition remains or hangs together in a vapor degreaser.

In another embodiment, the azeotrope-like compositions of the inventioncomprise from about 60 to about 97 weight percent of HCFC-141b, fromabout 2.0 to about 35.5 weight percent of dichlorotrifluoroethane, fromabout 1 to about 4.7 weight percent of methanol and from about 0 01 toabout 1.0 weight percent nitromethane.

In a preferred embodiment of the invention, the constant-boilingcompositions of the invention comprise from about 70 to about 94 weightpercent of HCFC-141b, from about 5 to about 26.0 weight percent ofdichlorotrifluoroethane, from about 1.0 to about 4.0 weight percent ofmethanol and from about 0.02 to about 1.0 weight percent nitromethane.

In a still more preferred embodiment of the invention, theconstant-boiling compositions of the invention comprise from about 75 toabout 90 weight percent of HCFC-141b, from about 7.5 to about 21.0weight percent of dichlorotrifluoroethane, from about 2.0 to about 3.8weight percent of methanol and from about 0.02 to about 0.5 weightpercent nitromethane.

In the most preferred embodiment of the invention, the constant-boilingcompositions of the invention comprise from about 80.0 to about 90.0weight percent HCFC-141b, about 7.5 to about 16.0 weight percentdichlorotrifluoroethane, about 0.02 to about 0.2 weight percentnitromethane and about 2.5 to about 3.8 weight percent methanol whichexhibits a boiling point of about 30.2° C. at 760 mm Hg.

The azeotrope-like compositions of the invention containing a mixture ofHCFC-123 and HCFC-123a behave as an azeotrope-like composition becausethe separate quaternary azeotropic compositions with HCFC-123 andHCFC-123a have boiling points so close to one another as to beindistinguishable for practical purposes.

The precise or true azeotrope compositions have not been determined buthave been ascertained to be within the indicated ranges. Regardless ofwhere the true azeotropes lie, all compositions within the indicatedranges, as well as certain compositions outside the indicated ranges,are azeotrope-like, as defined more particularly below.

It has been found that these azeotrope-like compositions are on thewhole nonflammable liquids, i.e. exhibit no flash point when tested bythe Tag Open Cup test method--ASTM D 1310-86.

From fundamental principles, the thermodynamic state of a fluid isdefined by four variables: pressure, temperature, liquid composition andvapor composition, or P-T-X-Y, respectively. An azeotrope is a uniquecharacteristic of a system of two or more components where X and Y areequal at the stated P and T. In practice, this means that the componentsof a mixture cannot be separated during distillation, and therefore areuseful in vapor phase solvent cleaning as described above.

For the purpose of this discussion, by azeotrope-like composition isintended to mean that the composition behaves like a true azeotrope interms of its constant boiling characteristics or tendency not tofractionate upon boiling or evaporation. Such composition may or may notbe a true azeotrope. Thus, in such compositions, the composition of thevapor formed during boiling or evaporation is identical or substantiallyidentical to the original liquid composition. Hence, during boiling orevaporation, the liquid composition, if it changes at all, changes onlyto a minimal or negligible extent. This is to be contrasted withnon-azeotrope-like compositions in which during boiling or evaporation,the liquid composition changes to a substantial degree.

Thus, one way to determine whether a candidate mixture is "azeotropelike" within the meaning of this invention, is to distill a samplethereof under conditions (i.e., resolution--number of plates) whichwould be expected to separate the mixture into its separate components.If the mixture is non-azeotropic or non-azeotrope-like, the mixture willfractionate, i.e. separate into its various components with the lowestboiling component distilling off first, and so on. If the mixture isazeotrope-like, some finite amount of a first distillation cut will beobtained which contains all of the mixture components and which isconstant boiling or behaves as a single substance. This phenomenoncannot occur if the mixture is not azeotrope-like i.e., it is not partof an azeotropic system. If the degree of fractionation of the candidatemixture is unduly great, then a composition closer to the true azeotropemust be selected to minimize fractionation. Of course, upon distillationof an azeotrope-like composition such as in a vapor degreaser, the trueazeotrope will form and tend to concentrate.

It follows from the above that another characteristic of azeotrope-likecompositions is that there is a range of compositions containing thesame components in varying proportions which are azeotrope-like. Allsuch compositions are intended to be covered by the term azeotrope-likeas used herein. As an example, it is well known that at differingpressures, the composition of a given azeotrope will vary at leastslightly as does the boiling point of the composition. Thus, anazeotrope of A and B represents a unique type of relationship but with avariable composition depending on temperature and/or pressure.Accordingly, another way of defining azeotrope-like within the meaningof this invention is to state that such mixtures boil within about ±0.8°C. (at about 760 mm Hg) of the boiling point of the most preferredcompositions disclosed herein. With HCFC-141b, dichlorotrifluoroethane,ethanol and nitromethane, the preferred mixtures boil within about ±0.4°C. (at about 760 mm Hg) of 33.0° C. As is readily understood by personsskilled in the art, the boiling point of the azeotrope will vary withthe pressure.

In the process embodiment of the invention, the azeotrope-likecompositions of the invention may be used to clean solid surfaces bytreating said surfaces with said compositions in any manner well knownto the art such as by dipping or spraying or use of conventionaldegreasing apparatus.

The HCFC-141b, dichlorotrifluoroethane, nitromethane, methanol andethanol components of the novel solvent azeotrope-like compositions ofthe invention are known materials, preferably they should be used insufficiently high purity so as to avoid the introduction of adverseinfluences upon the solvency properties or constant boiling propertiesof the system.

Of the possible six binary combinations of the four components whichform the azeotrope-like mixtures of one embodiment of this invention:HCFC-141b, dichlorotrifluoroethane, nitromethane and ethanol, only twoare known to form azeotropes: HCFC-141b and ethanol (31.9° C. boilingpoint at 765 mm Hg), a minimum boiling azeotrope and nitromethane andethanol (76.0° C. boiling point at 760 mm Hg), a minimum boilingazeotrope. HCFC-141b and HCFC-123, HCFC-141b and nitromethane. HCFC-123and nitromethane, and HCFC-123 and ethanol, are not known to form binaryazeotropes.

Of the possible four ternary combinations of the four components whichform the azeotrope-like mixtures of one embodiment of this invention:HCFC-141b, dichlorotrifluoroethane, nitromethane and ethanol, only oneis known to form an azeotrope: HCFC-141b, dichlorotrifluoroethane andethanol (for HCFC-123, 31.6° C. boiling point at 760 mm Hg; forHCFC-123a, 32.0° C. boiling point at 760 mm Hg), a minimum boilingazeotrope. HCFC-141b, dichlorotrifluoroethane and nitromethane;HCFC-141b, nitromethane and ethanol; and dichlorotrifluoroethane,nitromethane and ethanol are not known to form ternary azeotropes.

The advantage of the quaternary systems over the ternary azeotrope,HCFC-141b/ethanol/dichlorotrifluoroethane, is their ability to inhibitcorrosion in metals.

Of the possible six binary combinations of the four components whichform the constant-boiling mixtures of one embodiment of this invention:HCFC-141b, dichlorotrifluoroethane, nitromethane and methanol, two areknown to form azeotropes: HCFC-141b and methanol (29.8° C. boiling pointat 765 mm Hg), a minimum boiling azeotrope; and methanol andnitromethane (64.4° C. boiling point at 760 mm Hg), a minimum boilingazeotrope. HCFC-141b and HCFC-123, HCFC-141b and nitromethane, andHCFC-123 and nitromethane are not known to form binary azeotropes.

Of the possible four ternary combinations of the four components whichform the constant-boiling mixtures of one embodiment of this invention:HCFC-141b, dichlorotrifluoroethane, nitromethane and methanol, three areknown to form azeotropes: HCFC-141b, nitromethane and methanol (29.4° C.boiling point at 760 mm Hg); dichlorotrifluoroethane, nitromethane andmethanol (27.2° C. boiling point at 760 mm Hg for HCFC-123 and 30.6° C.boiling point at 760 mm Hg for HCFC-123a); and HCFC-141b,dichlorotrifluoroethane and methanol (for HCFC-123, 29.6° C. boilingpoint at 760 mm Hg; for HCFC-123a. 29.7° C. boiling point at 760 mm Hg).HCFC-141b, dichlorotrifluoroethane and nitromethane is not known to formternary azeotropes.

It should be understood that the present compositions may includeadditional components so as to form new azeotrope-like compositions. Anysuch compositions are considered to be within the scope of the presentinvention as long as the compositions are constant-boiling oressentially constant-boiling and contain all of the essential componentsdescribed herein.

The present invention is more fully illustrated by the followingnon-limiting Examples.

EXAMPLES 1-2

These examples confirm the existence of azeotrope-like mixtures between1,1-dichloro-1-fluoroethane, ethanol, dichlorotrifluoroethane andnitromethane via the method of distillation. These examples alsoillustrate that these mixtures do not fractionate during distillation.

A 5-plate Oldershaw distillation column with a cold water condensedautomatic liquid dividing head was used for these examples. For Example1, the distillation column was charged with approximately 360 grams of89.9 weight percent HCFC-141b, 8.1 weight percent HCFC-123, 2.0 weightpercent ethanol and 0.2 weight percent nitromethane which was heatedunder total reflux for about an hour to ensure equilibration. A refluxratio of 2:1 was employed for this particular distillation.Approximately 50 percent of the original charges were collected in foursimilar-sized overhead fractions. The compositions of these fractionswere analyzed using gas chromatography. Table I shows the compositionsof the starting materials. The averages of the distillate fractions andthe overhead temperatures are quite constant within the uncertaintyassociated with determining the compositions, indicating that themixtures are constant boiling or azeotrope-like.

                  TABLE I                                                         ______________________________________                                        Example                                                                              HCFC-141b  HCFC-123   ETOH  Nitromethane                               ______________________________________                                        Starting Material (WT. %)                                                     1      89.9       8.1        2.0   0.2                                        2      77.6       20.2       2.0   0.2                                        Distillate Fractions (WT. %)                                                  1      90.3       8.3        1.3   0.05                                       2      77.2       21.7       1.0   0.08                                       ______________________________________                                                                       Boiling Point (°C.)                            Boiling   Barometric    Corrected to                                   Example                                                                              Point (°C.)                                                                      Pressure (mm Hg)                                                                            760 mm Hg                                      ______________________________________                                        1      32.9      743           33.3                                           2      32.3      743           32.6                                                            mean          33.0 ± 0.4                                  ______________________________________                                    

The compositions of the invention are useful as solvents in a variety ofvapor degreasing, cold cleaning and solvent cleaning applicationsincluding defluxing.

EXAMPLE 3-4

To illustrate the azeotrope-like nature of the mixtures of thisinvention under conditions of actual use in vapor phase degreasingoperation, a vapor phase degreasing machine was charged with a preferredazeotrope-like mixture in accordance with the invention, comprisingabout 87.0 weight percent HCFC-141b, about 9.6 weight percent HCFC-123,about 3.1 weight percent methanol and 0.3 weight percent nitromethane.The mixture was evaluated for its constant boiling or non-segregatingcharacteristics. The vapor phase degreasing machine utilized was a smallwater-cooled, three-sump vapor phase degreaser, which represents a typeof system configuration comparable to machine types in the field todaywhich would present the most rigorous test of solvent segregatingbehavior. Specifically, the degreaser employed to demonstrate theinvention contained two overflowing rinse-sumps and a boil-sump. Theboil-sump was electrically heated, and contained a low-level shut-offswitch. Solvent vapors in the degreaser were condensed on water-cooledstainless-steel coils. The capacity of the unit was approximately 1.2gallons. This degreaser was very similar to Baron Blakeslee 2 LLV 3-sumpdegreasers which are quite commonly used in commercial establishments.

The solvent charge was brought to reflux and the compositions in therinse sump and the boil sump where the overflow from the work sump wasbrought to the mixture boiling point, were determined with a perkinElmer 8500 gas chromatograph. The temperature of the liquid in the boilsump was monitored with a thermocouple temperature sensing deviceaccurate to ±0.2° C. Refluxing was continued for 48 hours and sumpcompositions were monitored throughout this time. A mixture wasconsidered constant boiling or non-segregating if the maximumconcentration difference between sumps for any mixture component was ±2sigma around the mean value. Sigma is a standard deviation unit and itis our experience from many observations of vapor degreaser performancethat commercial "azeotrope-like" vapor phase degreasing solvents exhibitat least a ±2 sigma variation in composition with time and yet producevery satisfactory non-segregating cleaning behavior.

If the mixture were not azeotrope-like, the high boiling componentswould very quickly concentrate in the boil sump and be depleted in therinse sump. This did not happen. Also, the concentration of eachcomponent in the sumps stayed well within ±2 sigma. These resultsindicate that the compositions of this invention will not segregate inany types of large-scale commercial vapor degreasers, thereby avoidingpotential safety, performance and handling problems. The preferredcomposition tested was also found to not have a flash point according torecommended procedure ASTM D 1310-86 (Tag Open Cup). The details of thesegregation study are shown in Table 2.

Example 3 was repeated for Example 4 except that the composition was aconstant-boiling mixture of 70.1 weight percent HCFC-141b, 26.8 weightpercent HCFC-123, 0.2 weight percent nitromethane and 2.9 weight percentmethanol. The results are shown in Table 2 below.

                  TABLE 2                                                         ______________________________________                                        48 Hours                                                                              Initial      Condensate Boil                                                  Composition  Sump       Sump                                          ______________________________________                                        Example 3                                                                     R-141b  87.0         86.5       86.4                                          R-123   9.6          9.7        10.0                                          MeOH    3.1          3.6         2.6                                          NM      0.3          0.2         1.0                                          Temp                 25.9° C.                                                                          29.7° C.                               Prs                  739 mm Hg. 739 mm Hg.                                    Example 4                                                                     R-141b  70.1         70.1       70.1                                          R-123   26.8         27.0       25.5                                          MeOH    2.9          2.8         3.1                                          NM      0.2           0.06       0.8                                          Temp                 27.0° C.                                                                          29.8° C.                               Prs                  739 mm Hg. 739 mm Hg.                                    ______________________________________                                    

Having described the invention in detail and by reference to preferredembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of theinvention defined in the appended claims.

What is claimed is:
 1. Azeotrope-like compositions consistingessentially of from about 62.5 to about 97.9 weight percent1,1-dichloro-1-fluoroethane, from about 2.0 to about 35.5 weight percentdichlorotrifluoroethane selected from the group consisting of1,1-dichloro-2,2,2-trifluoroethane, 1,2-dichloro-1,2,2-trifluoroethane,and mixtures thereof, from about 0.02 to about 0.3 weight percentnitromethane, and from about 0.1 to about 3.0 weight percent ethanolwherein said azeotrope-like components consist of said1,1-dichloro-1-fluoroethane, said dichlorotrifluoroethane, saidnitromethane, and said ethanol and said azeotrope-like compositions boilat about 33.0° C. at 760 mm Hg.
 2. The azeotrope-like compositionsaccording to claim 1 wherein said dichlorotrifluoroethane is1,2-dichloro-1,2,2-trifluoroethane.
 3. The azeotrope-like compositionsaccording to claim 1 wherein said dichlorotrifluoroethane is1,1-dichloro-2,2,2-trifluoroethane.
 4. The azeotrope-like compositionsaccording to claim 1 consisting essentially of from about 72.0 to about94.7 weight percent said 1,1-dichloro-1-fluoroethane, from about 3.0 toabout 26.0 weight percent said dichlorotrifluoroethane, from about 0.05to about 0.3 weight percent said nitromethane and from about 0.3 toabout 2.0 weight percent said ethanol.
 5. The azeotrope-likecompositions according to claim 1 consisting essentially of from about75.0 to about 90.0 weight percent said 1,1-dichloro-1-fluoroethane, fromabout 5.0 to about 24.7 weight percent said dichlorotrifluoroethane,from about 0.05 to about 0.2 weight percent said nitromethane and fromabout 0.3 to about 1.8 weight percent said ethanol.
 6. Theazeotrope-like compositions according to claim 1 consisting essentiallyof about 77.2 to about 90.0 weight percent said1,1-dichloro-1-fluoroethane, about 5.0 to about 21.7 weight percent saiddichlorotrifluoroethane, from about 0.05 to about 0.2 weight percentsaid nitromethane and about 0.3 to about 1.5 weight percent saidethanol.
 7. The azeotrope-like compositions according to claim 6 whereinsaid dichlorotrifluoroethane is 1,2-dichloro-1,2,2-trifluoroethane. 8.The azeotrope-like compositions according to claim 6 wherein saiddichlorotrifluoroethane is 1,1-dichloro-2,2,2-trifluoroethane.
 9. TheAzeotrope-like compositions of claim 1 which boil at 33.0° C.±4° C. at760 mm Hg.
 10. Azeotrope-like compositions consisting essentially ofabout 60 to about 97 weight percent 1,1-dichloro-1-fluoroethane, about 2to about 35.5 weight percent dichlorotrifluoroethane selected from thegroup consisting of 1,1-dichloro-2,2,2-trifluoroethane,1,2-dichloro-1,2,2-trifluoroethane, and mixtures thereof, about 0.01 toabout 1.0 weight percent nitromethane, and about 1 to about 4.7 weightpercent methanol wherein said azeotrope-like components consist of said1,1-dichloro-1-fluorethane, said dichlorotrifluoroethane, saidnitromethane, and said methanol and said azeotrope-like compositionsboil at about 30.2° C. at 760 mm Hg.
 11. The compositions of claim 10wherein said dichlorotrifluoroethane is1,2-dichloro-1,2,2-trifluoroethane.
 12. The compositions of claim 10wherein said dichlorotrifluoroethane is1,1-dichloro-2,2,2-trifluoroethane.
 13. The compositions of claim 10wherein said compositions consist essentially of about 70 to about 94weight percent said 1,1-dichloro-1-fluoroethane, about 5 to about 26weight percent said dichlorotrifluoroethane, about 0.02 to about 1weight percent said nitromethane and about 1 to about 4 weight percentsaid methanol.
 14. The compositions of claim 10 wherein saidcompositions consist essentially of about 75 to about 90 weight percentsaid 1,1-dichloro-1-fluoroethane, about 7.5 to about 21 weight percentsaid dichlorotrifluoroethane, about 0.02 to about 0.5 weight percentsaid nitromethane and about 2 to about 3.8 weight percent said methanol.15. The compositions of claim 10 wherein said compositions consistessentially of about 80 to about 90 weight percent said1,1-dichloro-1-fluoroethane, about 7.5 to about 16.0 weight percent saiddichlorotrifluoroethane, about 0.02 to about 0.2 weight percent saidnitromethane and about 2.5 to about 3.8 weight percent said methanol.16. The compositions of claim 15 wherein said dichlorotrifluoroethane is1,2-dichloro-1,2,2-trifluoroethane.
 17. The compositions of claim 15wherein said dichlorotrifluoroethane is1,1-dichloro-2,2,2-trifluoroethane.
 18. A method of cleaning a solidsurface which comprises treating said surface with said azeotrope-likecomposition as defined in claim
 1. 19. A method of cleaning a solidsurface which comprises treating said surface with said azeotrope-likecomposition as defined in claim
 4. 20. A method of cleaning a solidsurface which comprises treating said surface with said azeotrope-likecomposition as defined in claim 10.